/Engine/Source/Runtime/Engine/Classes/GameFramework/Actor.h
GetActorClassDefaultComponentFetches the first component of ActorClass's CDO which match the requested component class. Will include the components added via the BP editor (whichAActor.GetComponentsfails to do for CDOs).
template<typename TComponentClass, typename> static const TComponentClass * GetActorClassDefaultComponent ( const [TSubclassOf](API\Runtime\CoreUObject\Templates\TSubclassOf)< [AActor](API\Runtime\Engine\GameFramework\AActor) > & InActorClass )